Clean up: Instead of open-coded flag manipulation, use test_bit() and
clear_bit() just like all other accessors of the state->flag field.
This also eliminates several unnecessary implicit integer type
conversions.
To make it absolutely clear what is going on, a number of comments
are introduced.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>